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%I #12 Oct 25 2023 16:03:30
%S 0,1,2,6,8,12,15,19,30,31,110,175,358,456,475,1359,1741,2061,6062,
%T 7568,10027,10732,27761,52018,75456,133543,136291,203048
%N Numbers k such that (182*10^k + 1)/3 is prime.
%C For k>1, numbers such that the digits 60 followed by k-1 occurrences of the digit 6 followed by the digit 7 is prime (see Example section).
%C a(29) > 3*10^5.
%H Makoto Kamada, <a href="https://stdkmd.net/nrr">Factorization of near-repdigit-related numbers</a>.
%H Makoto Kamada, <a href="https://stdkmd.net/nrr/prime/primedifficulty.txt">Search for 606w7</a>.
%e 2 is in this sequence because (182*10^2 + 1)/3 = 6067 is prime.
%e Initial terms and primes associated:
%e a(1) = 0, 61;
%e a(2) = 1, 607;
%e a(3) = 2, 6067;
%e a(4) = 6, 60666667;
%e a(5) = 8, 6066666667; etc.
%t Select[Range[0, 100000], PrimeQ[(182*10^# + 1)/3] &]
%Y Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.
%K nonn,more,hard
%O 1,3
%A _Robert Price_, Feb 13 2017
%E a(26)-a(27) from _Robert Price_, Feb 27 2020
%E a(28) from _Robert Price_, Oct 25 2023
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